What is the relation between Photovoltaic and Nearly Zero Energy Buildings?

The present need to, dramatically, increase the renewable part of our energy supply is now pushing to maximize the Photovoltaic (PV) use on the building skin, thus making aesthetical and building integration a key issue of contemporary architecture. Moreover, until today photovoltaic installations on buildings have been primarily built for the production of energy, putting this way the aesthetic and functionality of architectural design in second place. The European Directive 2010/31/EU establishes that starting from 2020 all new buildings will have to be Nearly Zero Energy (NZEBs). This will have an impact both in the building design (passive strategies, appropriate materials choice and systems efficiency) by reducing the energy demand by the building itself, and in the diffusion of renewable energies on-site (such as Photovoltaic or Solar Thermal) , which will produce the remaining part of energy needed. Given the growing popularity of solar technologies, in particular of PV systems, it is necessary to prevent their indiscriminate use in building through a proper and innovative integration.

What does BIPV mean?

The acronym BiPV refers to systems and concepts in which the photovoltaic element takes, in addition to the function of producing electricity, the role of a building element. In recent years, the integration of PV modules in architecture is strongly evolving. New BiPV products, with their innovative sizes and characteristics, are able to fully replace some building materials. By BiPV element we mean a building component used as part of the building envelope (roof tiles, façade cladding, glazed surfaces, etc.), sun protection devices (shading), etc. and any other architectural element that is necessary for the proper functioning of the building. The BiPV concept, as typical in building and architecture, involves two complementary aspects. The first one is the multi-functionality of the solar component that is the functional/constructive integration. On the other side there is the aesthetic integration that is the architectural quality of integration.

What is the multifunctionality of BIPV?

Since many years, the use of solar technologies in the building is called by the community “Building Integrated”. PV systems are generally considered to be building-integrated, if the PV modules replace a building component providing its technological roles. Thus the building function of PV (that represents its multi-functionality) is a prerequisite for the integrity of the building’s functionality. If the integrated PV module is dismounted (e.g. in the case of structurally fixed modules, dismounting includes the adjacent building component), it has to be replaced by an adequate building component able to satisfy the same technological requirements (e.g. water-tightness, mechanical resistance, etc.). Therefore the BiPV system, depending on the specific context, has to satisfy basic requirements for building component such as mechanical resistance and stability, safety in case of fire, hygiene and health of people, safety and accessibility in use, protection against noise as well as energy economy and sustainable use of natural resources. Likewise inherent electro-technical properties of PV such as power generation, yield, electromagnetic shielding etc., do not qualify alone, by themselves, PV elements as building integrated.